National Weather Service United States Department of Commerce

...October 1st-5th Historic Rainfall and Flooding...


Retrospective Story Map of Historic Rainfall and Flooding October 1st-5th 2015

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Event Synopsis


Event Synopsis...

A cold front came through late night Wed Sep 30th and stalled near the coast for several days due to an upper level flow that paralled the surface front. An upper level trough closed off and remained nearly stationary to our west for several days. A surface area of low pressure developed along the front near the coast or just offshore, while a strong area of surface high pressure built into eastern Canada. This resulted in a strong low level flow off the Atlantic. This flow pattern brought a long, deep fetch of moisture northwestward towards the Carolinas from Hurricane Joaquin.

The combination of upper divergence and lift east of the closed low, and a strong persistent low level flow off the Atlantic and associated low level moisture convergence and isentropic lift, along with a plume of tropical moisture getting entrained into the system, provided a band of heavy rain showers and a few thunderstorms that at times trained over the same areas and persisted for many hours.

The heaviest rain occurred from the Columbia vicinity, southeastward across lower Richland Co, Sumter Co, Calhoun Co, Clarendon Co and lower Orangeburg Co. The heaviest rainfall occurred late Saturday night Oct 3rd into the morning hours of Sunday Oct 4th.  At times, rainfall rates of 2” inches per hour affected those locations for several hours.  This heavy and persistant rainfall occurred over urban areas where runoff rates were high, and over grounds already wet from recent rains. This heavy rainfall caused numerous roadway and bridge closings due to dam failures, along with culvert and pipe washouts across the region. Numerous life saving swift water rescues were performed..

In general, a significant gradient in rainfall amounts occurred in our CWA, with 1-2 inches west of the Savannah River, 2-4 inches just on the east side of the Savannah River, with amounts ramping up to around 10 inches eastward into West Central Midlands, with 10-20 inches from Columbia SE across the Eastern Midlands. The NWS had been advertising this very heavy rainfall and flooding potential well in advance of the event.

During this event, Columbia Metro Airport set a new record for both the greatest one and two day rainfall totals.

Columbia Metro Airport Rainfall Record

Greatest 1-day rainfall…. 6.71 inches set on October 4, 2015
Old 1-day rainfall record….. 5.79 inches set on July 9, 1959

Greatest 2-day rainfall….. 10.28 inches set on October 3-4, 2015
Old 2-day rainfall record….. 7.69 inches set on August 16-17, 1949



Please note, some images below are rather large and may take a while to load on a slow connection.

Below is a map showing Rainfall Totals through the Evening of October 4th.  Just below the image is the latest updated Public Information Statement detailing location amounts.